Motor vehicle article carriers have long been known to be useful for increasing the cargo capacity of motor vehicles. Generally, the carriers comprise rigid bars which are mounted to and supported above a vehicle body panel to provide a solid support that does not deform the finished body panel, and avoids abrasive contact between the cargo and the vehicle body panel. However, many of the previously known article carriers were rigid structures which could not be adjusted to fit differently sized articles or parcels, and the parcels had to be strapped or otherwise tied to the article carrier in order to maintain the articles in position as the vehicles objected to movement of the vehicle and environmental conditions.
One previously known improvement for retaining articles in a fixed position on the article carrier was to provide crossbars extending between longitudinal rails, the crossbars being constructed as clamps to grip and hold articles in a fixed position on the carrier. In particular, some previously known carriers particularly adapted for carrying skis include upper arms pivotally connected to lower arms of the crossbars so that they can be pivoted up to receive a set of skis between padded layers on the upper and lower arms. The upper arms pivoted downwardly into pressing engagement with the ski and the lower arm member and a locking means clamps the upper arm in its compression position. However, such article carriers are particularly adapted for long relatively narrow structures, and are ill suited for a wide variety of cargo shapes and sizes.
Another previously known improvement in article carrying devices includes crossbars which were slidably received in elongated channels of longitudinal rail members. Typically, the crossbars include a clamping means such as cams or other locking members in order to retain the crossbar in a fixed position within the channel of the rail as desired. However, the open channels and the clamping members, including the particularly shaped surfaces or complex clamping elements, are exposed to environmental conditions and subject to the deforming, obstructive or corrosive effects of temperature, humidity, wind and debris. For example, ice accumulation could impede installation or movement of the crossbar within the channel.
In addition, specifications and standards for vehicle mounted luggage carriers are often established before a particular design or style of luggage carrier may be accepted for production. For example, the cross bars may be required to withstand particular force and torques when locked in position in the side rails and withstand deformation as loads carried by the carrier may shift in response to vehicle motion and deceleration. However, the resistance to removal or displacement of the crossbars is in large part a function of the particular connection used to retain the crossbar in position on the rail. For example, where a member clamps over a crossbar portion to retain it in a fixed position along the rail, that member and its retainers bear the entire force of maintaining the crossbar under the member. Accordingly, the forces are not distributed throughout the entire carrier structure in a manner which could reduce the thickness or strength of the retaining member and its associated mounting hardware.